In order to operate effectively, printers must be able to perform various tasks during a print cycle, including picking up a sheet of paper, feeding it through the printer, and then kicking it out through the printer's output port. Such tasks are generally accomplished using a plurality of motor-driven gear trains, each such train being configured to execute a different one of the defined tasks. A problem with this arrangement, however, is that it requires the use of numerous, complex and costly gear mechanisms, driving the price of most single-sheet printers beyond the budgetary limits of many potential printer purchasers.
One cost-saving approach to this problem has involved the use of a clutch which is selectively engagable with a single, motor-driven gear to bring about execution of each of the various tasks. An example of such an arrangement is set forth in U.S. Pat. No. 5,000,594, which names Beehler et al. as inventors and which is commonly owned herewith. In that patent, the inventors describe a clutch which is attached to a cam-like pivot, the pivot being used to direct a sheet of paper through a conventional print cycle. Upon engagement with the gear, the clutch drives the pivot from a spring-biased initial position to a task-performing position wherein the pivot directs execution of a particular task. Once the directed task is completed, the clutch is disengaged, allowing the pivot to return under spring bias to its initial position so that another task may be performed.
Although the just-described arrangement has simplified the mechanism required to perform conventional printer tasks, it has left room for further improvements. For example, one area of difficulty concerns the rate at which the pivot returns to its initial position once a task has been performed. Known printers have provided for unrestrained spring-biased return of the pivot to the first position, such return being halted only by collision of the pivot or clutch with a static stop. Such collision, in turn, has led to excessive stresses on the components involved and to an undesirable clanking sound. Additionally, pivot return in known printers cannot be stopped until the pivot reaches its initial position, potentially leading to missed opportunities of saved time or energy between the performance of consecutive tasks.